This invention relates to a method of controlling operation of an internal combustion engine, and more particularly, to a control method of this kind which is capable of suitably controlling the amount of fuel supplied to an internal combustion in dependence upon whether an exhaust gas recirculation control system associated with the engine is operating or not, etc.
A known method of controlling the supply of fuel to an internal combusion engine, such as disclosed by the assignee of the present application in Japanese Provisional Patent Publication (Kokai) No. 58-82037, includes storing in a memory basic fuel supply values conforming to a plurality of operating parameters of an internal combustion engine equipped with an exhaust gas recirculation control system, reading a value of the basic fuel supply values that corresponds to values of the operating parameters, correcting the read basic fuel supply value in dependence upon operating conditions of the engine, and controlling the amount of fuel supplied to the engine by using the corrected value.
With this conventional control method, two sets of map values of basic fuel supply values conforming to the plurality of operating parameters are provided, one for use when the exhaust gas recirculation control system is operating and one for use when it is not, and these sets of map values are stored in the memory. In order to store these two sets of map values, a read-only memory (hereinafter referred to as the "ROM") having a large storage capacity is needed. The additional memory capacity required results in a higher manufacturing cost. In particular, with the greater complexity of fuel supply control programs in recent years, there is a demand for larger memory capacity for the purpose of storing such programs. However, the aforementioned requirement for greater memory capacity needed to store the map values runs counter to this demand.